Obese people with sleep apnea who lose 10% of their weight have a good chance of improving their condition, a study shows.

"This is good news because it shows that a little bit of weight loss can go a long way when it comes to improving sleep apnea," says the study's lead author, Gary Foster, director of the Center for Obesity Research and Education at Temple University in Philadelphia.

Foster found in a previous research that 87% of obese patients with type 2 diabetes had sleep apnea and didn't know it.

In the first large-scale study to quantify the benefits of weight loss on the sleep disorder, Foster and researchers at four other medical centers and universities analyzed data on 264 obese patients with type 2 diabetes and sleep apnea - either mild, moderate or severe forms.

Participants were divided into two groups. One followed an intense lifestyle intervention program for a year that included a portion-controlled diet with liquid meal replacements, frozen food entrees and snack bars; an exercise recommendation of doing 175 minutes of physical activity such as brisk walking a week; and behavior-modification suggestions.

The other control group attended three informational sessions about managing their diabetes. Findings, reported in Monday's issue of the Archives of Internal Medicine:

At the end of the first year, the intervention group lost an average of 24 pounds or about 10% of their starting weight. The other group lost about 1 pound.

Overall, sleep apnea improved in the weight-loss group and worsened in the control group.

The greatest benefit of weight loss was found in males, those with the most severe sleep apnea and those who lost the most weight.

Twice as many people in the diet group moved to a less-severe category, for example from moderate to mild. About 14% of the people in the diet group had complete remission of the disorder.

For obese people who want to lose weight, Foster recommends keeping track of what they eat, using portion-controlled meals such as Healthy Choice and Lean Cuisine and walking 30 minutes a day.

The study was supported by a grant from the National Institutes of Health.